All the other maps in the pack open just fine. I double-checked that I didn't have a corrupt download by re-downloading the archive a second time; same result. Is the map corrupt in the archive, or is this only happening to me? If so, might anyone know how to solve it?

Oh yeah, I should add that there are NO mutators in Oldskool's active list. So it's not a mutator issue.

Yeah, the reason I default to the D3D is because it automatically takes care of the superspeed issue. If you use OpenGL you have to go into Advanced Options and set that FrameRateLimit or whatever it is (re the sticky thread on that topic). But a bit of convenience doesn't much matter if a map won't run!